The present invention relates to a method for drying workpieces, in particular metal sheets, provided with a fresh surface coating, wherein the workpieces are conveyed through a drying zone in a housing where the work-pieces have hot air applied to them in the process.
After they have been printed and/or coated, metal sheets are transported through a drying system by a workpiece conveyor device including a continuous belt. In the drying system, the metal sheets are held by the retaining frame of the continuous belt and are exposed to a hot air flow as they are transported through the drying zone in the process. At the end of the drying zone, the metal sheets have a solidified surface coating. Then they are removed from the workpiece conveyor device and are deposited, for example automatically, in a stack. The known method has a risk of condensate forming on the walls, ceilings or built in components of the housed drying zone. The condensate is mostly viscous. Upon accumulation of a sufficient quantity, the condensate can run down or drip off, causing the freshly coated metal sheets moving in the region to become contaminated and therefore unusable. Since the contamination occurs mostly only on individual metal sheets, it is impossible to ensure continuous production because of the laborious undertaking of separating the unusable workpieces. These contamination problem occur, in particular, when organosols, phenolic resins or special white pigmented coatings are used. The design of the dryer and the setting of its air budget also influence the problem of contamination. High degrees of contamination are to be expected given the short drying path in a double coating line.